How to compress a PDF
- Choose Compression: Basic for no quality loss, or Strong to shrink the images too.
- Select Choose files or drop your PDF on the box. You can add several files.
- Check the row. It shows the size before and after.
- Select Download. The new file ends in
-compressed.
If the file is locked, enter its password first. The compressed copy is saved without a password; you can add one again with Protect PDF.
Basic and Strong
Basic is lossless. It rewrites the file with object streams, which store many small objects together, and recompresses the data inside with the best Flate setting. Nothing visible changes. This helps most with files made by office software and scanners that wrote loose, poorly packed data.
Strong does everything Basic does and then looks at each picture. Photos and scans that are far sharper than a screen or office printer needs are scaled down to about 150 DPI and saved as JPEG at 70 percent quality. Pictures that are already small, or that would not get smaller, are left alone. Text, fonts, vector drawings and links are not touched.
Before and after, honestly
Every result shows the original size and the new size. If a file would end up larger, you get your original back with a note, so you never download something worse. Files that are mostly text, or were exported with compression already on, may save very little.
Tips for email limits
- Need under 10 MB or 25 MB for email? Try Basic first, then Strong.
- Scanned documents shrink the most, because each page is one big image.
- Strong mode lowers image quality a little. For print-quality work, keep the original and use Basic.
- Split a long file with Split PDF, or remove pages you do not need with Delete PDF pages.
- Compress pictures before making a PDF with Image compressor.
Compression is done with qpdf and pdf-lib on your device. Your document is never uploaded.